It is known in airplane operations applications to exchange data between airplanes and ground stations concerning atmospheric conditions, in order to improve the flight operations.
U.S. Pat. No. 6,937,937 describes measurement aboard a plurality of monitoring airplanes to record local atmospheric conditions. The recorded data is transmitted in real-time to ground-monitoring stations, capable of compiling the data to generate real-time three-dimensional maps of weather conditions aloft. Also, a set of predictive indicia can be created for a subscribing airplane. When requesting predictive indicia, the subscribing airplane may indicate information such as its current location, altitude, heading, and flight-path, so that the predictive indicia can be specifically tailored to the needs of the subscribing airplane.
It is suggested in U.S. Pat. No. 6,937,937, since it is expected that the size of data-batches uploaded to subscribing users will be greater than that downloaded from requesting users or from monitoring airplanes, to provide high bandwidth for uploads but lower bandwidth for downloads. However, taking into account the large number of radio transmissions related to flight control and airports, there is a need to keep any additional bandwidth requirements low. Further, U.S. Pat. No. 6,937,937 is not concerned with the need to reduce fuel-consumption and emissions from airplanes, especially on descent for landing.
The press information from The Swedish Civil Aviation Administration on Jan. 20, 2006, ‘Less noise and exhaust by using “green approach”’ (http://www.lfv.se/templates/LFV_ListArticle—39601.aspx) discloses a system creating an accurate airplane time navigation by providing a more precise estimated time of arrival. The flight management system of an airplane receives, shortly after take-off, from a ground control centre at the destination a message specifying the approach path that should be used at the destination. The flight management system calculates an arrival time based on the approach path and current flying conditions. The flight management system also calculates the time and position at which the airplane's descent to the destination should begin. This is done so as to provide an approach trajectory such that a minimum of engine thrust is used and the airplane essentially glides or coasts through its descent, reducing noise, exhaust gases and fuel-consumption. Such approach trajectories have become known as “green approaches” or CDA (Continuous Descent Approaches). The arrival time calculated by the flight management system is sent to the ground control centre, where it is inserted in a list of expected arrivals of a plurality of airplanes. If two or more arrivals should coincide, an additional message is sent to the airplane, stating an adjusted arrival time. The flight management system then makes a new calculation and adjusts the airplane's speed and/or trajectory, so that the landing can occur at the specified time. Such a speed adjustment can occur at the beginning of the flight. It should be mentioned that traditional airplane approaches normally involve a stepwise descent where engine thrust is increased intermittently and often the airplane is directed to a “holding pattern”; waiting for its time to land, resulting in large excesses of fuel-consumption, emissions, and noise.
The calculation of the time of the start of the airplane's descent is based partly on wind information, which can be received from a flight planning centre, and which could be several hours old. However, to provide effective information so as to reduce the fuel-consumption and emissions of descending airplanes, there is a need to improve said wind information, especially since “green approaches” are particularly sensitive to the wind patterns encountered during the descent.